Plasma Flow Generation due to the Nonlinear Alfvén Wave Propagation around a 3D Magnetic Null Point

Abstract The behavior of current density accumulation around the sharp gradient of magnetic field structure or a 3D magnetic null point and with the presence of finite plasma pressure is investigated. It has to be stated that in this setup, the fan plane locates at the xy plane and the spine axis aligns along the z-axis. Current density generation in presence of the plasma pressure that acts as a barrier for developing current density is less well understood. The shock-capturing Godunov-type PLUTO code is used to solve the magnetohydrodynamic set of equations in the context of wave-plasma energy transfer. It is shown that propagation of Alfvén waves in the vicinity of a 3D magnetic null point leads to current density excitations along the spine axis and also around the magnetic null point. Besides, it is pointed out the x component of current density has oscillatory behavior while the y and z components do not show this property. It is plausible that it happens because the fan plane encompasses separating unique topological regions, while the spine axis does not have this characteristic and is just a line without separate topological regions. Besides, current density generation results in plasma flow. It is found that the y component of the current density defines the x component of the plasma flow behavior, and the x component of the current density prescribes the behavior of the y component of the plasma flow.

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How Alfvén waves induce compressive flows in the neighborhood of a 2.5D magnetic null-point

Scientific Reports ◽

10.1038/s41598-020-70995-y ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

S. Sabri ◽

S. Vasheghani Farahani ◽

H. Ebadi ◽

S. Poedts

Keyword(s):

Current Density ◽

Null Point ◽

Alfven Wave ◽

Back Reaction ◽

Fast Wave ◽

Induced Current ◽

The Creation ◽

Reconnection Site ◽

Magnetic Null ◽

Magnetic Null Point

Abstract The aim of the present study is to provide insight on the induced compressive perturbations together with the modifications of the environmental parameters in the course of Alfvén wave interaction with a solar magnetic null-point. The shock-capturing Godunov-type code PLUTO is used to solve the set of ideal magnetohydrodynamic equations. The nonlinear effects connected with an initial Alfvén pulse nearing a magnetic null point induces fast and slow magnetoacoustic waves with anti phase conduct. The induced current density and flows are independent of the local plasma-$$\beta$$ β at the reconnection site. The induced inflows and outflows highly depend on the polarization. The inflows have a stronger effect compared to the outflows in both the x and y directions showing its peak in the x-direction. The dominant wave that couples to flows is the fast wave due to the in-phase harmony between perturbations of the compressive parameters and the fast wave. The induced current density possesses a steady orientation at the reconnection site which governs the diffusion or propagation of the waves. Induced perturbations by the nonlinear forces together with their back reaction on the Alfvén wave have a significant role in the current density excitation being responsible for the creation of inflows and outflows that are possible candidates for the creation of solar jets which has a significant contribution towards coronal seismology.

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Alfvén wave dynamics at the neighbourhood of a 2.5D magnetic null-point

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/sty1407 ◽

2018 ◽

Vol 479 (4) ◽

pp. 4991-4997 ◽

Cited By ~ 4

Author(s):

S Sabri ◽

S Vasheghani Farahani ◽

H Ebadi ◽

M Hosseinpour ◽

Z Fazel

Keyword(s):

Null Point ◽

Alfven Wave ◽

Wave Dynamics ◽

Magnetic Null ◽

Magnetic Null Point

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Nonlinear Alfvén wave dynamics at a 2D magnetic null point: ponderomotive force

Astronomy and Astrophysics ◽

10.1051/0004-6361/201321338 ◽

2013 ◽

Vol 555 ◽

pp. A86 ◽

Cited By ~ 7

Author(s):

J. O. Thurgood ◽

J. A. McLaughlin

Keyword(s):

Ponderomotive Force ◽

Null Point ◽

Alfven Wave ◽

Wave Dynamics ◽

Magnetic Null ◽

Magnetic Null Point

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Cluster Observation of Electrostatic Solitary Waves around Magnetic Null Point in Thin Current Sheet

Chinese Physics Letters ◽

10.1088/0256-307x/27/1/019401 ◽

2010 ◽

Vol 27 (1) ◽

pp. 019401 ◽

Cited By ~ 7

Author(s):

Li Shi-You ◽

Deng Xiao-Hua ◽

Zhou Meng ◽

Yuan Zhi-Gang ◽

Wang Jing-Fang ◽

...

Keyword(s):

Current Sheet ◽

Solitary Waves ◽

Null Point ◽

Thin Current Sheet ◽

Magnetic Null ◽

Magnetic Null Point

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Quasi-periodic Radio Bursts Associated with Fast-mode Waves near a Magnetic Null Point

The Astrophysical Journal ◽

10.3847/1538-4357/aa7d53 ◽

2017 ◽

Vol 844 (2) ◽

pp. 149 ◽

Cited By ~ 19

Author(s):

Pankaj Kumar ◽

Valery M. Nakariakov ◽

Kyung-Suk Cho

Keyword(s):

Null Point ◽

Radio Bursts ◽

Fast Mode ◽

Magnetic Null ◽

Magnetic Null Point

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Spatially Separated Electron and Proton Beams in a Simulated Solar Coronal Jet

The Astrophysical Journal ◽

10.3847/1538-4357/ac2e6d ◽

2021 ◽

Vol 923 (2) ◽

pp. 163

Author(s):

Ross Pallister ◽

Peter F. Wyper ◽

David I. Pontin ◽

C. Richard DeVore ◽

Federica Chiti

Keyword(s):

Particle Acceleration ◽

Particle Deposition ◽

Lower Boundary ◽

Impulsive Phase ◽

Null Point ◽

Solar Photosphere ◽

In Situ Observations ◽

Magnetic Null ◽

Magnetic Null Point

Abstract Magnetic reconnection is widely accepted to be a major contributor to nonthermal particle acceleration in the solar atmosphere. In this paper we investigate particle acceleration during the impulsive phase of a coronal jet, which involves bursty reconnection at a magnetic null point. A test-particle approach is employed, using electromagnetic fields from a magnetohydrodynamic simulation of such a jet. Protons and electrons are found to be accelerated nonthermally both downwards toward the domain’s lower boundary and the solar photosphere, and outwards along the axis of the coronal jet and into the heliosphere. A key finding is that a circular ribbon of particle deposition on the photosphere is predicted, with the protons and electrons concentrated in different parts of the ribbon. Furthermore, the outgoing protons and electrons form two spatially separated beams parallel to the axis of the jet, signatures that may be observable in in-situ observations of the heliosphere.

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